OP0305 THE BURDEN OF MULTIMORBIDITY IN ANCA-ASSOCIATED VASCULITIS: A COHORT STUDY
Authors: Z. Wallace, X. Fu, S. Srivatsan, Z. Williams, C. Cook, J. Hanberg, J. H. Stone, H. Choi, Y. Zhang
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> With improvements in the risks of relapse and mortality in ANCA-associated vasculitis (AAV), a better understanding of disease- and treatment-related complications in people with AAV is necessary to optimize outcomes and personalize care. Multimorbidity (MM) is a patient-centered approach to measuring complications and is defined as the presence of multiple chronic conditions[1]. MM is associated with risk of death and quality of life in other conditions. MM remains poorly understood in AAV[2]. <h3>Objectives</h3> To determine the burden of multimorbidity in AAV. <h3>Methods</h3> We used the 2002-2019 Mass General Brigham (MGB) AAV cohort: an inception cohort of consecutive MPO- or PR3-ANCA+ incident AAV cases at a multi-center healthcare system in New England, USA. Comparators without systemic rheumatic disease were identified from MGB and matched to cases (10:1 ratio) by encounter date, age, sex, and race. We adapted a definition of MM as the presence of ≥ 2 of 37 chronic conditions, identified by use of ICD-9/10 codes ≥ twice over ≥ 30 days[1]. Manifestations of AAV (e.g., kidney disease) were excluded from the MM definition. Conditions present ≥ 6 months prior to the index date (date of treatment initiation) were excluded. First, we determined the proportion of cases and comparators with MM using the Aalen-Johansen method, accounting for the competing risks of death and loss to follow up. Second, we used Cox proportional hazard models to estimate the hazard ratio (HR) of MM in cases vs comparators and restricted mean survival time to estimate days free of MM in cases vs comparators. Third, we used latent class analysis to characterize clusters of morbidity among people with MM. <h3>Results</h3> There were 547 cases matched to 5,259 comparators (Table 1); mean age was 59 years and the majority were female (61%) and white (88%). Median follow-up in cases and comparators was 102 months and 66 months, respectively. MM was substantially more common in cases vs comparators and AAV cases had nearly an 8-fold higher risk of MM vs comparators (Figure 1, HR 7.6, 95% CI 6.6-8.7). Over 5 years, each case had an average of 707 fewer days with MM than comparators (963.4 vs 1670.5 days, p&lt;0.001). At 1 year, two clusters of MM in AAV were identified with 76% and 24% captured in Clusters 1A and 1B, respectively. Hypertension and hyperlipidemia were common in Cluster 1A whereas Cluster 1B was characterized by painful conditions (e.g., headache, back pain, GERD). At 2 years, two clusters were identified with 82% and 18% captured in Clusters 2A and 2B. Cluster 2B was distinguished from 2A by a high burden of cardiovascular (CV) and pulmonary disease along with typical CV risk factors. At 5 years, three clusters were identified with 81%, 11%, and 8% captured in Cluster 5A, 5B, and 5C. Morbidities most common in Cluster 5A were hypertension and hyperlipidemia. Cluster 5B was distinguished by a higher burden of CV and pulmonary disease whereas Cluster 5C had the highest burden of certain glucocorticoid toxicities (e.g., osteoporosis, obesity, hypertension). <h3>Conclusion</h3> AAV is associated with a high burden of MM and carries a greater risk of MM than the general population. MM in AAV is characterized by clusters defined by morbidity burdens that vary over disease course and reflect a high impact of disease and its treatment. The development of interventions to prevent MM and minimize its impacts are needed. These findings identify an important direction for future investigations to improve the care and outcomes of patients with AAV. <h3>References</h3> [1]England BR, et al. Ann Rheum Dis 2021;80:286–92. [2]Sarica SH, et al. Arthritis Rheumatol 2021;73:651-9. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.